Drafting Device of a Textile Machine

ABSTRACT

A drafting device of a textile machine includes a roller and an opposed counter roller, each including a roller body and an axis of rotation, wherein the axis of rotation of one or both of the roller and the counter roller is mounted only at one end thereof. The roller is movably mounted between a resting position in which the roller body of the roller and of the counter roller are not in contact, and a load position in which the roller body of the roller and of the counter roller are pressed against one another along a contact region. The roller is movable from the resting position into a load position by moving into an intermediate position wherein the axes of rotation of the roller and of counter roller are aligned such that the contact region between the roller and the counter roller is smaller than in the load position of the roller.

FIELD OF THE INVENTION

The present invention relates to a drafting device of a textile machine that includes at least one roller and at least one corresponding counter roller, between which a fiber structure can be guided and clamped. The roller and the counter roller each have a roller body and an axis of rotation. The axis of rotation of the roller and that of the counter roller are supported on only one end, the roller being mounted movably between a resting position, in which the roller bodies of the roller and the counter roller do not come in contact, and a load position, in which the roller bodies of the roller and the counter roller are pressed against one another. The roller is movable into an intermediate position in transition from the resting position to the load position. In the intermediate position, the roller bodies of the roller and the counter roller only come in contact.

BACKGROUND

Drafting devices are known in the prior art and are used with ring spinning machines or air spinning machines, for example, where they are used for drafting (other conventional terms for this are “drawing” or “stretching”) and thus for making the fiber structure supplied to the spinning machine more uniform.

Drafting devices are used in so-called spinning mill preparation machines, in particular for stretching, which are connected upstream from the corresponding spinning machines and also serve to make the fiber structure more uniform. In principle, the aforementioned drafting devices comprise two or more roller configurations, each having corresponding rollers and counter rollers in turn, which are ultimately driven at increasing rotational speeds to cause the fiber structure to be drawn in the direction of transport of the fiber structure passing through the drafting device.

While it is known that the rollers and counter rollers can be mounted on both sides by means of two laterally protruding axes of rotation, it is also a state-of-the-art step to operate at least some of the rollers and/or counter rollers on only one end over their respective axis of rotation in a bearing. In this case, the axis of rotation usually is colinear with the axis of rotation of the roller body of the corresponding roller and/or counter roller and can be supported by means of a ball bearing or roller bearing in a support of the drafting device.

If a fiber structure is now passed between a roller and its counter roller in the load position, as is the case during operation of the drafting device, this exerts a force on the respective roller bodies running at a right angle to their axis of rotation. To be sure, this force is countered by an opposing force, implemented by the support of the respective axes of rotation. However, this opposing force decreases with an increase in the distance from the bearing of the respective axis of rotation. In addition, there is a certain flexural elasticity of the axes of rotation, as well as unavoidable play between the roller bodies and the axis of rotation and/or the axis of rotation and the corresponding bearing.

Therefore, as a result, the clamping force acting on the fiber structure due to the pressure of the roller and the counter roller in the load position is not constant in the direction of the axes of rotation of the roller and the counter roller but instead decreases with an increase in the distance from the bearings—resulting in a negative effect on the drawing results.

SUMMARY OF THE INVENTION

An object of the present invention is to counteract this disadvantage and to propose a drafting device with which the fiber structure to be drawn is subjected to a uniform treatment over its width (i.e., at a right angle to the direction of transport) with a clamping force generated by the roller and the counter roller.

Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

The objects are achieved by a drafting device having the features set forth herein.

According to the invention, the drafting device is characterized in that the axes of rotation of the roller and the counter roller are directed toward one another in the intermediate position (in which the roller bodies of the roller and the counter roller do not come in contact), such that the roller bodies of the roller and the counter roller have a joint contact region that is smaller in the axial direction of the axis of rotation of the roller than in the load position, in which the roller bodies of the roller and the counter roller are pressed against one another (the position mentioned last is assumed by the roller during the drafting operation while a fiber structure is being transported through the drafting device and thereby drawn). While the roller and the counter roller are fully in contact with one another in the load position (at least before the fiber structure is guided into the drafting device) and thereby form a clamping line, the roller and the counter roller in the intermediate position come in contact only over a contact region smaller than the aforementioned clamping line. If the roller is then moved against the counter roller and thus into the load position, then any curving of the axes of rotation that might occur and/or any play present in the aforementioned regions can be compensated, so that an almost constant or even a completely constant clamping force prevails over the entire clamping line formed by the roller and the counter roller as a result. In this way, a fiber structure inserted into the drafting device is acted upon with a uniform force over its total width (i.e., its spatial extent running perpendicular to the direction of transport), resulting in a particularly uniform drawing of the fiber structure.

Moreover, it should be pointed out here that the actual value of the pressing force during the drafting operation should be adjustable through appropriate load elements, wherein the load elements are designed as pneumatic cylinders, for example, with the help of which a load force can be transferred to the bearing of the roller or counter roller to press the roller and the counter roller against one another.

In addition, it should also be pointed out in general that the terms “roller” and “counter roller” which are used here say nothing about the mutual spatial orientation. It is thus possible for the roller to be arranged at a right angle above the counter roller, so that the direction of transport of the drafting device is horizontal. Likewise, the direction of transport of the drafting device may run at a right angle or obliquely to the horizontal and to the vertical so that the roller and the counter roller may be arranged side by side or offset obliquely to one another.

Furthermore, it should be pointed out that the following embodiments usually relate to a roller and its corresponding counter roller. The drafting device according to the invention should of course comprise a plurality of roller configurations, each having at least one roller and at least one counter roller. Finally, it should be pointed out that a plurality of counter rollers may be associated with one roller of the drafting device and vice versa, and it is also conceivable for a belt to be wrapped around one or more rollers and/or counter rollers to be able to guide the fiber structure in a particularly reliable manner.

Within the context of the present invention, however, it is sufficient if at least one roller and/or counter roller of a roller arrangement can be moved between the aforementioned resting position and the aforementioned intermediate position.

It is advantageous if, in the intermediate position, the contact region has a contact surface which is smaller than that in the load position by a factor of at least 10, preferably a factor of at least 20, especially preferably a factor of at least 50. The roller and the counter roller are preferably in contact with one another in the load position (without a fiber structure in between), such that they form a joint clamping line, preferably 2 cm to 8 cm long. The contact surface here is essentially linear, wherein the line may have a width of a few tenths of a millimeter up to several millimeters. The line preferably has a width of 0.2 mm to 3.0 mm, especially preferably 1.0 mm to 2.5 mm. However, the contact surface in the intermediate position is embodied in the form of dots. The contact surface is at least significantly smaller than that in the load position, so that the aforementioned advantages with regard to the uniform clamping force acting on the fiber structure during drafting operation can be implemented.

In addition, it is advantageous if, in the intermediate position, the roller bodies of the roller and the counter roller come in contact only in the area of their respective end faces. In this case, the axes of rotation of the roller bodies of the roller and the counter roller do not run parallel to one another in the intermediate position. The axes of rotation instead are arranged obliquely to one another, but they may also lie in the same plane. In this case, in contrast with a possible alternative oblique orientation of the axes of rotation, the imaginary extensions of the axes of rotation of the roller bodies would intersect.

It is also extremely advantageous if both the axis of rotation of the roller and the axis of rotation of the counter roller are mounted rotatably at one end by means of a bearing of the drafting device, wherein the roller bodies of the roller and the counter roller in the intermediate position come in contact only in the region of their end faces, which face away from the bearings. If the roller is then moved from the intermediate position into its load position, the contact region, which is at first essentially in the form of dots, develops into an essentially linear contact region, so that the roller and the counter roller ultimately form a joint clamping line with the mutual pressing force of the roller bodies being as constant as possible over the length thereof.

It is especially advantageous if the axes of rotation of the roller and the counter roller lie in a common plane, at least in the load position. The axes of rotation in the aforementioned position also preferably run parallel to one another (in at least some sections) to form the aforementioned clamping line (wherein, alternatively, a skewed orientation of the aforementioned axes of rotation would also be conceivable). It is equally conceivable for the respective axes of rotation to also lie in a common plane in the intermediate position and/or in the aforementioned resting position.

It is also advantageous if the axes of rotation in the intermediate position form an angle α between 0° and 2.0°, preferably between 0.1 and 1.0°, especially preferably between 0.1° and 0.8°. The axes of rotation of the roller and the counter roller are thus oriented only minimally obliquely to one another in the intermediate position, wherein the aforementioned angle in any case is selected to be greater than 0° in order to rule out a parallel orientation. In this context, it should be pointed out that the aforementioned angle need not have the same value with all roller configurations (=roller(s) and corresponding counter roller(s)) of a drafting device. Instead, the angle between the individual roller configurations may vary, so that the amount may depend on the respective diameters of the axes of rotation and/or the roller bodies, for example, and/or the configuration within the drafting device (a drafting device usually has a pair of input rollers, one or more central roller pairs and one output roller pair, wherein fiber structure passes over the individual roller pairs one after the other, as seen in the transport direction).

It is especially advantageous if the axis of rotation of the roller and the axis of rotation of the counter roller run obliquely to one another in the intermediate position. The roller in this case is not moved back and forth between the load position and the resting position in a direction linear and perpendicular to the respective axes of rotation. Instead, the movement takes place in a pivoting movement, so that, in the intermediate position, the imaginary extensions of the aforementioned axes of rotation do not intersect.

It is advantageous in this context if the drafting device has a support that is pivotable about a pivot axis and comprises a bearing of the roller, wherein the pivot axis of the support and the axis of rotation of the roller run obliquely to one another at least in the intermediate position. The support may accommodate one or more rollers by means of corresponding bearings and can preferably be secured in the load position of the rollers with the help of retaining elements that operate pneumatically, mechanically and/or electromechanically. In addition, there may be counter support, which serves to accommodate and/or support the counter roller, the counter support preferably being secured rigidly in the corresponding textile machine and/or its drafting device. The counter support may accommodate one or more counter rollers by means of corresponding bearings. Finally, it is also conceivable, alternatively or additionally, for the pivot axis of the support and the axis of rotation of the counter roller to run obliquely relative to one another, at least in the intermediate position. If the support is pivoted in such a way that the rollers are in their load positions, then the axes of rotation of the roller and the counter roller of at least one roller configuration should lie in a common plane.

It is especially advantageous if the drafting device has a support that is pivotable about a pivot axis and comprises the bearing of the roller, wherein the pivot axis of the support and the axis of rotation of the roller run parallel to one another at least in the intermediate position, and wherein the axis of rotation of the roller and the pivot axis of the support run skewed to one another at least in the intermediate position. In this case, the smaller contact area between the roller and the counter roller is achieved in the intermediate position by the fact that the axis of rotation of the roller in a frontal view of the drafting device (as seen in the direction opposite the direction of transport) is mounted obliquely in the support. In this case, the support is pivotable about a pivot axis preferably running horizontally.

In an alternative embodiment, it may also be advantageous if the drafting device has a support that is pivotable about a pivot axis and comprises the bearing of the roller, wherein the pivot axis of the support and the axis of rotation of the roller run parallel to one another at least in the intermediate position, and wherein the axis of rotation of the counter roller and the pivot axis of the support run skewed to one another, at least in the intermediate position. In this case, both the axis of rotation of the roller and the pivot axis run obliquely to the horizontal in the aforementioned frontal view, so that it is ensured that again in this case, the roller will be in contact with the counter roller in only a small contact area in the intermediate position.

The bearing of the axis of rotation in the support and/or counter support may be rotatable or rotationally fixed. In the case of a rotationally fixed support of the axes of rotation in the support, the roller is held rotatably on the axis of rotation. Accordingly, a rotationally fixed connection of the roller and the axis of rotation is to be provided in the case of a rotatable bearing of the axis of rotation in the support.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional advantages of the invention are described in the following embodiments, in which:

FIG. 1 shows a schematic side view of a textile machine equipped with a drafting device;

FIG. 2 shows a perspective view of a detail of a drafting device according to the invention, wherein the rollers are in their resting positions;

FIG. 3 shows the detail according to FIG. 2, wherein the rollers are in their load positions;

FIG. 4 shows the detail according to FIG. 2, wherein the rollers are in their intermediate positions; and

FIG. 5 shows a perspective view of an alternative embodiment of a detail of a drafting device according to the invention, wherein the rollers are also in their intermediate positions.

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

FIG. 1 shows an air spinning machine as an example of a textile machine 2, which may be equipped with a drafting device 1 according to the invention. However, it should be pointed out in general at this point that the drafting device 1 according to the invention may also be used in a so-called drawing frame or in other spinning machines, for example, a ring spinning machine.

The air spinning machine shown as an example in FIG. 1 is preferably used to produce so-called roving 16. Roving 16 is yarn containing a relatively small amount of cover fibers, i.e., a yarn in which the winding fibers are wrapped relatively loosely around the inner core (preferably untwisted), so that the yarn remains twistable. This is crucial if the roving 16 thus produced is or must be twisted to be processable further accordingly (wherein this drafting device 1 may also be designed according to the present invention).

The air spinning machine comprises in general a drafting device 1 with at least two roller configurations arranged one after the other in a direction of transport T of the drafting device 1, serving to twist a fiber structure 5. Each roller configuration comprises at least one roller 3 and a corresponding counter roller 4, which is mounted to be rotatable about corresponding axes of rotation 7 and between which the fiber structure 5 can be passed with clamping (for reasons of simplicity, only one of the axes of rotation 7 of the rollers 3 and one of the axes of rotation 7 of the counter rollers 4 are provided with reference numerals).

Furthermore, the air spinning machine shown here in principle comprises a spinneret 21 at a distance from the drafting device 1 and having an interior eddy chamber (known from the prior art and therefore not illustrated here) and a yarn-forming element protruding into the eddy chamber, also known from the prior art and therefore not illustrated here. The fiber sliver 5 and/or at least a portion of the fibers of the fiber sliver 5 is/are provided with a protective twist in the spinneret 21.

Likewise, the air spinning machine may have a draw-off unit 15 which preferably has two draw-off rollers 14 that can rotate about an axis of rotation 7, as well as a bobbin device 18 for the roving 16 connected downstream from the draw-off unit 15. The bobbin device in turn preferably comprises a bushing drive 19 plus at least one bushing receptacle, which is known in principle and is connected to the bushing drive 19 and to which a bushing 17 can be secured and can be induced to rotate with the help of the bushing drive 19 in order to be able to wind the roving 16, having been traversed by a traversing device 20, onto the bushing 17. The air spinning machine operates according to a special air spinning method. To form the roving 16, the fiber sliver 5 is guided in a transport direction T over an intake opening (not shown) into the eddy chamber of the spinneret 21 where it receives a protective twist, i.e., at least some of the fibers of the fiber sliver 5 are captured by an air stream generated by suitably positioned air jets. Some of the fibers are thereby pulled out of the fiber structure 5 at least some distance and wound around the tip of a yarn-forming element protruding into the eddy chamber.

Ultimately, the fibers of the fiber sliver 5 are drawn out of the eddy chamber over an intake opening of the yarn-forming element and a draw-off channel arranged inside the yarn-forming element and connected to the intake opening. Finally, the free fiber ends here are also drawn onto a spiral path in the direction of the intake opening, and in doing so, are wrapped as winding fibers around the core fibers running centrally, thereby resulting in a roving 16 having the desired protective twist.

Finally, the roving 16 has a residual drawing capacity due to the only partial twist of the fibers, this residual drawing capacity being indispensable for further processing of the roving 16 in a downstream spinning machine, for example, a ring spinning machine. However, conventional air spinning devices impart such a strong twist to the fiber sliver 5 that the necessary drawing after yarn production is no longer possible. In this case, this is also desirable because traditional air spinning machines are designed to produce a finished yarn, which should usually be characterized by a great strength.

FIG. 2 shows a detail of an drafting device 1 according to the invention, which can be used in the air spinning machine shown in FIG. 1, for example. The drafting device 1 comprises a plurality of rollers 3 and a plurality of counter rollers 4, which correspond to the rollers 3 and each of which has a roller body 6 and an axis of rotation 7, which serves to provide rotatable mounting of the respective roller body 6, wherein the axes of rotation 7 are mounted in bearings 11 (merely indicated in FIGS. 2 and 3). The bearing support of the axis of rotation 7 in the bearings 11 may be either rotatable or rotationally fixed. In the case of a rotationally fixed bearing of the axes of rotation 7 in the bearings 11, the roller body 6 is held rotatably on the axis of rotation 7. Accordingly, with a rotatable bearing support of the axis of rotation 7 in the bearing 11, a rotationally fixed restraint of the roller body 6 on the axis of rotation 7 is to be provided.

Furthermore, FIG. 2 shows, among other things, that the rollers 3 are preferably mounted in a support 12 and that the counter rollers 4 are mounted in a corresponding counter support 9. The bearing support here is unilateral, i.e., the respective axes of rotation 7 each extend between only one of the two front ends 10 of the corresponding roller bodies 6 and the respective support 12 and/or counter support 9 (of course, each roller 3 or group of rollers 3 may be supported in a separate support 12 in order to be able to adjust the mutual spacings of the rollers 3; the same thing also applies according to the counter rollers and their counter supports 9).

The core of the invention is derived from a combined view of FIGS. 2 to 4. First, FIG. 2 shows the condition of the drafting device 1, in which the rollers 3 are in their resting position, i.e., the roller bodies 6 of the roller 3 and the counter roller 4 are not in contact. The rollers 3 preferably assume this position while the drafting device 1 is stopped, such that the rollers 3 and/or counter rollers 4 are not driven and the fiber sliver 5 has been and/or is to be removed from the drafting device 1.

Before or shortly after the drafting device 1 is or has been charged in a transport direction T with a fiber sliver 5, the rollers 3 are moved into their load position shown in FIG. 3, wherein this can take place, for example, by pivoting the support 12 about a pivot axis 13 (the pivot axis 13 is shown only in FIG. 3).

With traditional drafting devices 1, there is the disadvantage here that the mutual pressing force of the individual roller bodies 6 pressed against one another is not constant along their contact region 8 (which is linear in FIG. 3) because the individual bearings 11 have a certain play and the axes of rotation 7 usually have at least minimal sagging. A fiber sliver 5 passed between the roller bodies 6 is therefore not uniformly subjected to load over its width running perpendicular to the transport direction T so that uneven drawing of the individual segments of the fiber sliver 5 occurs.

To counteract this disadvantage, it is now proposed within the scope of the present invention that the axes of rotation 7 of the rollers 3 designed according to the invention shall have an orientation in an intermediate position as illustrated in FIG. 4, which results in the roller bodies 6 of the roller 3 having a joint contact region 8 and the counter roller 4 having a common contact area 8, which is smaller as seen in the axial direction of the axis of rotation 7 of the roller 3 than in the load position illustrated in FIG. 3.

As is apparent from FIG. 4 in this context, the roller bodies 6 of the roller 3 and the corresponding counter roller 4 preferably have only an essentially dot-shaped contact region 8 in the intermediate position wherein this can be implemented by the fact that the axes of rotation 7 of the roller 3 and counter roller 4 form an angle α in the aforementioned intermediate position, the size of this angle being different than 0° (reference is made to the general description with regard to advantageous angle sizes).

If rollers 3 mounted in this way are moved out of their intermediate position and into their load position illustrated in FIG. 3 by pivoting the support 12, then any play in the bearings 11 and/or a slight curving of the individual axes of rotation 7 are balanced in such a way that the pressing force is constant over the entire contact region 8 between the roller 3 and the counter roller 4 (ideal case). A fiber sliver 5 guided with clamping between the corresponding roller bodies 6 is uniformly loaded here over its width so that the fiber sliver 5 can be drawn in a particularly homogeneous manner.

Although FIG. 4 illustrates an approach in which the axes of rotation 7 of the rollers 3 are mounted obliquely in the support 12, and the support 12 can be pivoted about a pivot axis 13 running parallel to the axes of rotation 7 of the counter rollers 4, FIG. 5 shows an alternative embodiment which is characterized in that the axes of rotation 7 of the rollers 3 are aligned parallel with the pivot axis 13 of the support 12. In this case, both the pivot axis 13 of the support and the axes of rotation 7 of the rollers 3 form an angle α (shown in an exaggerated size in FIG. 5) with the axes of rotation 7 of the counter rollers 4 in a front view of the drafting device 1, the size of said angle differing from 0°, as seen in the intermediate position in FIG. 5. Thus, again in this variant, it is ensured that the roller bodies 6 of the rollers 3 and the counter rollers 4 each have only an essentially dot-shaped contact region 8 when the rollers 3 are in their intermediate position.

The present invention is not limited to the embodiments illustrated and described here. Modifications within the scope of the patent claims are also possible as is any combination of the features described here, even if they are illustrated in different embodiments and described in different portions of the description and/or claims.

LIST OF REFERENCE NUMERALS

-   1 Drafting device -   2 Textile machine -   3 Roller -   4 Counter roller -   5 Fiber sliver -   6 Roller body -   7 Axis of rotation -   8 Contact region -   9 Counter support -   10 Front end -   11 Bearing -   12 Support -   13 Pivot axis of the support -   14 Draw-off roller -   15 Draw-off unit -   16 Roving -   17 Bushing -   18 Bobbin device -   19 Bushing drive -   20 Traversing device -   21 Spinneret -   α Angle formed by the axes of rotation of the roller and the counter     roller in the intermediate position -   T Direction of transport 

1-10. (canceled)
 11. A drafting device of a textile machine, comprising: a roller, and an opposed counter roller, wherein a fiber sliver is guidable between the roller and counter roller; the roller and the counter roller each comprising a roller body and an axis of rotation, wherein the axis of rotation of one or both of the roller and the counter roller is mounted only at one end thereof; the roller movably mounted between a resting position in which the roller body of the roller and of the counter roller are not in contact, and a load position in which the roller body of the roller and of the counter roller are pressed against one another along a contact region; the roller movable from the resting position into a load position by moving into an intermediate position; wherein in the intermediate position, the axes of rotation of the roller and of counter roller are aligned such that the contact region between the roller body of the roller and of the counter roller is smaller in an axial direction of the axis of rotation of the roller than in the load position of the roller.
 12. The drafting device according to claim 11, wherein the contact region in the intermediate position of the roller is smaller than that in the load position by a factor of at least
 10. 13. The drafting device according to claim 11, wherein in the intermediate position of the roller, the contact region is adjacent a front end of the roller and the counter roller opposite the mounted end.
 14. The drafting device according to claim 13, wherein the axes of rotation of the roller and of the counter roller are mounted to rotate at the mounted end by means of a bearing on the drafting device.
 15. The drafting device according to claim 11, wherein the axes of rotation of the roller and of the counter roller lie in a common plane at least in the load position.
 16. The drafting device according to claim 11, wherein in the intermediate position, the axes of rotation of the roller and of the counter roller form an angle (α) greater than 0° and up to or equal to 2.0.
 17. The drafting device according to claim 16, wherein in the intermediate position, the axes of rotation of the roller and of the counter roller run skewed to one another.
 18. The drafting device according to claim 11, further comprising a support, the support comprising a bearing for the mounted end of the roller, the support pivotable about a pivot axis, wherein the pivot axis of the support and the axis of rotation of one or both of the roller and the counter roller are skewed relative to one another in the intermediate position of the roller.
 19. The drafting device according to claim 11, further comprising a support, the support comprising a bearing for the mounted end of the roller, the support pivotable about a pivot axis, wherein the pivot axis of the support and the axis of rotation of the counter roller are parallel to one another, and the axis of rotation of the roller and the pivot axis of the support run skewed to one another at least in the intermediate position of the roller.
 20. The drafting device according to claim 11, further comprising a support, the support comprising a bearing for the mounted end of the roller, the support pivotable about a pivot axis, wherein the pivot axis of the support and the axis of rotation of the roller are parallel to one another, and the axis of rotation of the counter roller and the pivot axis of the support run skewed to one another at least in the intermediate position of the roller. 